Nutrition Chapter 9

Functions of Water in the Body

• Universal Solvent: Water can dissolve a wide variety of solutes, making it essential for nutrient transportation and waste removal.

• Body Temperature Regulation: Water helps regulate temperature through perspiration (evaporation cooling mechanism).

• Lubrication: Acts as a lubricant in joints, gastrointestinal (GI) tract (saliva, mucus), and as a cushion for the brain and spinal cord (cerebrospinal fluid).

Control Mechanisms for Water Intake and Output

• Water Balance Regulation:

  • Hormonal Control: Antidiuretic hormone (ADH) signals kidneys to absorb more water. Aldosterone promotes sodium and water retention in kidneys.

  • Osmosis: The movement of water from areas of low solute concentration to high solute concentration through cell membranes.

Recommendations and Sources of Water

• Recommended Intakes:

  • Adult Females: 2.7 L (~11 cups)

  • Adult Males: 3.7 L (~15 cups)

• Sources:

  • Fruits and vegetables (over 80% water content)

  • Metabolic water produced during nutrient metabolism.

Health Consequences of Dehydration

• Signs of Dehydration:

  • Thirst and lack of appetite at 1-2% loss of body water.

  • Increased fatigue, dizziness, headache at 4% loss.

  • Severe consequences (kidney failure, coma) at 10% loss.

Electrolytes: Essential Minerals in the Body

• Key Electrolytes:

  • Sodium, Potassium, Chloride, and Phosphate.

• Functions:

  • Regulate fluid balance, acid-base balance, and nerve impulse transmission.

Dietary Sources and Requirements of Electrolytes

• Sodium: 2300 mg/day recommended. Sources include table salt, processed foods.

• Potassium: 4700 mg/day recommended. Found in fruits, vegetables, beans, and whole grains.

• Chloride: AI is 2300 mg/day. Found in table salt and some vegetables.

Fluid Balance Regulation and Blood Pressure Control

• Lifestyle Modifications to Lower Blood Pressure:

  • DASH Diet: Rich in fruits, vegetables, low-fat dairy, and low in sodium and saturated fats.

  • Physical Activity: Regular aerobic exercise contributes to blood pressure management.

  • Hydration and Sodium Management: Monitor sodium intake and stay hydrated to promote vascular health.

Monitoring Hydration Status

• Urine Color: A clear or pale yellow indicates proper hydration; dark yellow indicates dehydration.

• Thirst: Not a reliable indicator of hydration; it's better to maintain fluid intake proactively, especially in athletes or during illness.

Risks of Overhydrogenation

• Water Intoxication: Caused by excessive water intake diluting sodium levels leading to potential brain swelling and heart dysfunction.

Summary of Key Calcium and Other Minerals in Blood Pressure Management

• Focus on Calcium, Magnesium, and Potassium for hypertension management; they help relax blood vessels.

• Sodium Sensitivity: Vulnerability to high sodium leading to elevated blood pressure in some individuals.